Electric energy routing device for distributed photovoltaic access low-voltage power distribution network

Abstract

The utility model provides an electric energy routing device for distributed photovoltaic access to a low-voltage power distribution network, which relates to the technical field of energy routers and comprises a main circuit module, an intelligent control module, a communication module, a monitoring and protecting module, an information processing module, an energy storage module and an interface module. The electric energy routing device for accessing the distributed photovoltaic system to the low-voltage power distribution network adopts a modularized multi-level structure, is provided with a high-voltage alternating current port and a high-voltage direct current port, and can be interconnected with a high-voltage alternating current power distribution network and a high-voltage direct current power distribution network; the withstand voltage level of the high-voltage level of the electric energy router can be improved through modular multi-level superposition, redundancy control is easy to realize, and the reliability of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy routers, and particularly relates to an electric energy routing device for distributed photovoltaic access to a low-voltage distribution network. Background Technique

[0002] Distributed photovoltaic power generation specifically refers to a distributed power generation system that uses photovoltaic modules to directly convert solar energy into electric energy. Distributed photovoltaic power generation is a new type of power generation and comprehensive energy utilization method with broad development prospects. With the rapid development of the concept and practice of the energy Internet, and at the same time accompanied by the rapid progress of power electronics technology, related concepts such as electronic transformers, intelligent transformers, power electronic transformers, and energy routers have been successively proposed. As a key node power supply device for future AC / DC distribution network systems, the energy router has multiple high-voltage AC / DC ports, uses advanced power electronics technology for voltage conversion and power transmission, can realize flexible control of the AC / DC distribution network power flow and mutual backup, and form an interconnected, peer-to-peer, and shared AC / DC distribution node. The energy router should not only have a fault isolation function, but also have the ability to limit short-circuit current and correct fault voltage, improve the autonomous ability of the distribution node, form a system-level measure to cope with the transient fault crossing of the AC / DC distribution network, and combine the fault crossing ability of terminal renewable energy power generation equipment and loads to jointly improve the safety and continuous power supply of the distribution network. However, the existing energy routers do not provide medium- and low-voltage DC interfaces, which is not conducive to the access of distributed renewable energy and DC loads, and there are also problems of low power conversion efficiency and low volume power density. Content of the Utility Model

[0003] Aiming at the defect problems of the above-mentioned existing technologies, the utility model provides an electric energy routing device for distributed photovoltaic access to a low-voltage distribution network, which adopts a modular multilevel structure and has a high-voltage AC port and a high-voltage DC port, and can interconnect high-voltage AC and DC distribution networks.

[0004] To achieve the above purposes, the utility model is realized through the following technical solutions:

[0005] A power routing device for distributed photovoltaic access to low-voltage distribution networks, comprising a main circuit module, an intelligent control module, a communication module, a monitoring and protection module, an information processing module, an energy storage module, and an interface module; the main circuit module is the core for the power routing device to achieve power conversion control, and has functions of voltage conversion and AC / DC power conversion; the intelligent control module is connected to the main circuit module, and is used to achieve intelligent control and autonomous operation of the power routing device, as well as energy management and coordinated optimization with the distribution network / microgrid; one end of the monitoring and protection module and the information processing module is connected to the main circuit module, and the other end is connected to the communication model. The monitoring and protection module is used for the monitoring and protection functions of the power routing device itself, and the information processing module is used to achieve the acquisition, transmission and processing of electrical quantity information inside and outside the power routing device; the communication module is connected to the intelligent control module by wired or wireless means for information transmission; the energy storage module is connected to the main circuit model and is used for energy storage and coordinated control to achieve functions such as power balance at each port, peak shaving and valley filling, power quality control, and off-grid short-term power support; the interface module is connected to the main circuit module and is used to provide selectable power interfaces.

[0006] According to an embodiment of the present invention, the interface module includes an AC distribution network interface module, a DC distribution network interface module, a distributed power source interface module, a distributed energy storage interface module, an AC load interface module, and a DC load interface module.

[0007] According to an embodiment of the present invention, the core controller of the intelligent control module is TMS320F28335.

[0008] According to an embodiment of the present invention, the intelligent control module is connected to the communication module through RS485 or CAN bus.

[0009] According to an embodiment of the present invention, the intelligent control module communicates with the communication module through ModBus TCP / IP.

[0010] According to an embodiment of the present invention, the main circuit module includes a high-voltage cascaded sub-module, a voltage transformation and isolation cascaded sub-module, and a low-voltage inverter sub-module. The high-voltage cascaded sub-module, the voltage transformation and isolation cascaded sub-module, and the low-voltage inverter sub-module are connected in sequence. The high-voltage cascaded sub-module is formed by connecting in series greater than or equal to 1 full-bridge module or half-bridge module, and the voltage transformation and isolation cascaded sub-module is formed by connecting in series greater than or equal to 1 full-bridge module or half-bridge module.

[0011] According to an embodiment of the present utility model, the high-voltage cascaded sub-module is a three-phase circuit. Each phase is divided into upper and lower bridge arms, and each bridge arm is composed of m cascaded H-bridges, where m is greater than or equal to 1. The output terminal of the m-th H-bridge of the upper bridge arm of each phase is connected to the high-voltage AC interface through an inductor, and the output terminal of the first H-bridge of the lower bridge arm of each phase is connected to the high-voltage AC interface through an inductor.

[0012] According to an embodiment of the present utility model, the transformer isolation cascaded sub-module includes a primary side and a secondary side of the transformer. The primary side of the transformer includes two upper bridge arms, two lower bridge arms, and a coupling inductor. The upper and lower bridge arms on the same phase are connected through the coupling inductor. The upper and lower bridge arms are respectively composed of n cascaded H-bridges, where n is greater than or equal to 1. The secondary side of the transformer includes x rectifier bridges, where x is greater than or equal to 1, and all the rectifier bridges are connected in parallel.

[0013] According to an embodiment of the present utility model, the low-voltage inverter sub-module is composed of a three-phase bridge and a filter, and the filter is an LCL filter.

[0014] The beneficial effects of the present utility model: An electric energy routing device for distributed photovoltaic access to a low-voltage distribution network, adopting a modular multilevel structure, having high-voltage AC ports and high-voltage DC ports, and can interconnect high-voltage AC and DC distribution networks; the withstand voltage level of the high-voltage stage of the electric energy router can be improved through modular multilevel superposition, and redundant control is easy to implement, improving system reliability; the sub-module can adopt different types of structures such as a half-bridge or full-bridge sub-module, a half-bridge / full-bridge hybrid module, etc. according to the actual situation. The topological structure of the electric energy routing device of the present utility model has the advantages of bidirectional power controllability, multiple ports, electrical isolation and fault ride-through, redundant design, etc., and has good flexibility and scalability, and is suitable for high-power applications in medium-voltage and high-voltage AC-DC distribution networks. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 is the principle block diagram of the electric energy routing device of the present utility model;

[0017] Figure 2 is the structure diagram of the high-voltage cascaded sub-module of the present utility model;

[0018] Figure 3 is the structure diagram of the transformer isolation cascaded sub-module of the present utility model;

[0019] Figure 4 It is a structural diagram of a low-voltage inverter sub-module. Specific implementation manners

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0021] Combined with Figure 1 , a power routing device for distributed photovoltaic access to a low-voltage distribution network includes a main circuit module, an intelligent control module, a communication module, a monitoring and protection module, an information processing module, an energy storage module, and an interface module. The main circuit module is the core for the power routing device to achieve power conversion control, and it has functions of voltage conversion and AC / DC power conversion; the intelligent control module is connected to the main circuit module and is used to realize the intelligent control and autonomous operation of the power routing device, as well as the energy management and coordinated optimization with the distribution network / microgrid; one end of the monitoring and protection module and the information processing module is connected to the main circuit module, and the other end is connected to the communication model. The monitoring and protection module is used for the monitoring and protection functions of the power routing device itself, and the information processing module is used to realize the acquisition, transmission and processing of electrical quantity information inside and outside the power routing device; the communication module is connected to the intelligent control module by wire or wireless means and is used for information transmission; the energy storage module is connected to the main circuit model and is used for energy storage and coordinated control to achieve functions such as power balance at each port, peak shaving and valley filling, power quality control and off-grid short-term power support; the interface module is connected to the main circuit module and is used to provide selectable power interfaces.

[0022] The interface module includes an AC distribution network interface module, a DC distribution network interface module, a distributed power source interface module, a distributed energy storage interface module, an AC load interface module, and a DC load interface module.

[0023] The core controller of the intelligent control module is TMS320F28335. The intelligent control module is connected to the communication module through RS485 or CAN bus. The intelligent control module communicates with the communication module through ModBus TCP / IP.

[0024] Considering the voltage level, capacity and functional requirements of the power router comprehensively, the power routing device of the present utility model is applicable to a modular multilevel converter for interconnected AC / DC power grids with multiple voltage levels. The main circuit module of the power routing device includes a high-voltage cascaded sub-module, a step-down isolation cascaded sub-module, and a low-voltage inverter sub-module. The high-voltage cascaded sub-module, the step-down isolation cascaded sub-module, and the low-voltage inverter sub-module are connected in sequence. The high-voltage cascaded sub-module is composed of one or more full-bridge modules or half-bridge modules connected in series, and the step-down isolation cascaded sub-module is composed of one or more full-bridge modules or half-bridge modules connected in series.

[0025] Combined with Figure 2 , the high-voltage cascaded sub-module is a three-phase circuit. Each phase is divided into upper and lower bridge arms. Each bridge arm is composed of m H-bridges connected in cascade, where m is greater than or equal to 1. The output terminal of the m-th H-bridge of the upper bridge arm of each phase is connected to the high-voltage AC interface through an inductor, and the output terminal of the first H-bridge of the lower bridge arm of each phase is connected to the high-voltage AC interface through an inductor.

[0026] Combined with Figure 3 , the step-down isolation cascaded sub-module includes a primary side and a secondary side of a transformer. The primary side of the transformer includes two upper bridge arms, two lower bridge arms, and a coupling inductor. The upper and lower bridge arms on the same phase are connected through the coupling inductor. The upper and lower bridge arms are respectively composed of n H-bridges connected in cascade, where n is greater than or equal to 1. The secondary side of the transformer includes x rectifier bridges, where x is greater than or equal to 1, and all rectifier bridges are connected in parallel.

[0027] Combined with Figure 4 , the low-voltage inverter sub-module is composed of a three-phase bridge and a filter. The filter is an LCL filter.

[0028] In summary, in the embodiment of the present utility model, the power routing device for distributed photovoltaic access to a low-voltage distribution network adopts a modular multilevel structure, has high-voltage AC ports and high-voltage DC ports, and can interconnect high-voltage AC and DC distribution networks. By modular multilevel superposition, the voltage withstand level of the high-voltage stage of the power router can be improved, and redundant control is easy to implement, improving system reliability. The sub-module can adopt different types of structures such as based on half-bridge or full-bridge sub-modules, based on half-bridge / full-bridge hybrid modules, etc. according to the actual situation. The topological structure of the power routing device of the present utility model has the advantages of bidirectional controllability of power, multiple ports, electrical isolation and fault ride-through, redundant design, etc., and has good flexibility and scalability, and is suitable for high-power applications in medium-voltage and high-voltage AC / DC distribution networks.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric energy routing device for connecting distributed photovoltaic power to a low-voltage distribution network, characterized in that: It includes a main circuit module, an intelligent control module, a communication module, a monitoring and protection module, an information processing module, an energy storage module, and an interface module; the main circuit module is the core of the electric energy routing device to realize the electric energy conversion control, and has the functions of voltage conversion and AC / DC power conversion; the intelligent control module is connected to the main circuit module, and is used to realize the intelligent control and autonomous operation of the electric energy routing device, as well as the energy management and coordinated optimization with the distribution network / microgrid; one end of the monitoring and protection module and the information processing module are connected to the main circuit module, and the other end is connected to the communication model; the monitoring and protection module is used for the monitoring and protection function of the electric energy routing device itself, and the information processing module is used to realize the electrical quantity information collection, transmission and processing inside and outside the electric energy routing device; the communication module is connected to the intelligent control module by wire or wireless means for information transmission; the energy storage module is connected to the main circuit model, and is used for electric energy storage and coordinated control to realize the power balance of each port, peak shaving and valley filling, power quality control and off-grid short-time power support functions; the interface module is connected to the main circuit module, and is used to provide an optional electric energy interface.

2. An electric energy routing device for distributed photovoltaic access to a low-voltage distribution network as claimed in claim 1, characterized in that: The interface modules include an AC distribution network interface module, a DC distribution network interface module, a distributed power supply interface module, a distributed energy storage interface module, an AC load interface module, and a DC load interface module.

3. The electric energy routing device for distributed photovoltaic access to a low-voltage distribution network as claimed in claim 1, characterized in that: The core controller of the intelligent control module is TMS320F28335.

4. The electric energy routing device for connecting distributed photovoltaic power to a low-voltage power distribution network as claimed in claim 3, characterized in that: The intelligent control module is connected to the communication module via RS485 or CAN bus.

5. The electric energy routing device for distributed photovoltaic access to a low-voltage distribution network as claimed in claim 4, characterized in that: The intelligent control module communicates with the communication module via ModBus TCP / IP.

6. The electric energy routing device for distributed photovoltaic access to a low-voltage distribution network as claimed in claim 1, characterized in that: The main circuit module includes a high-voltage cascade submodule, a transformer isolation cascade submodule, and a low-voltage inverter submodule. The high-voltage cascade submodule, the transformer isolation cascade submodule, and the low-voltage inverter submodule are connected in sequence. The high-voltage cascade submodule is connected in series by more than or equal to one full-bridge module or half-bridge module, and the transformer isolation cascade submodule is connected in series by more than or equal to one full-bridge module or half-bridge module.

7. The electric energy routing device for connecting distributed photovoltaic power to a low-voltage distribution network as claimed in claim 6, characterized in that: The high-voltage cascade submodule is a three-phase circuit, each phase is divided into two upper and lower bridge arms, each bridge arm is composed of m H-bridge cascades, and m is greater than or equal to 1; the output end of the mth H-bridge of the upper bridge arm of each phase is connected to the high-voltage AC interface through an inductor, and the output end of the 1st H-bridge of the lower bridge arm of each phase is connected to the high-voltage AC interface through an inductor.

8. The electric energy routing device for connecting distributed photovoltaic power to a low-voltage power distribution network as claimed in claim 6, characterized in that: The transformer isolation cascade submodule includes a primary side and a secondary side of a transformer, wherein the primary side of the transformer includes two upper bridge arms, two lower bridge arms, and a coupled inductor, wherein the upper and lower bridge arms on the same phase are connected via a coupled inductor, and the upper and lower bridge arms are respectively composed of n H-bridge cascades, where n is greater than or equal to 1; and the secondary side of the transformer includes x rectifier bridges, where x is greater than or equal to 1, and all rectifier bridges are connected in parallel.

9. The electric energy routing device for connecting distributed photovoltaic power to a low-voltage distribution network as claimed in claim 6, characterized in that: The low voltage inverter submodule is composed of a three-phase bridge and a filter, and the filter is an LCL filter.

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